Polychloroprene cement cured with carbon disulfide, lower alkylaminoalcohols and lower polyalkylamines



United States Patent POLYCHLOROPRENE CEMENT CURED WITH CARBON DISULFIDE,LOWER ALKYLAMINO- ALCOHOLS AND LOWER POLYALKYLAMINES William E. Tann,Akron, Ohio, assignor to The Firestone Tfirehda Rubber Company, Akron,Ohio, a corporation 0 io No Drawing. Application August 21, 1957 SerialNo. 679,526

( This invention relates to improved neoprene (rubbery chloroprenepolymer) cements and more particularly to vulcanizable neoprene cementscontaining a combination of stabilizing agents and vulcanizationaccelerators as specified herein. The term cement ineludes coatings,adhesives and dispersions wherein a.

estate renders the neoprene cement entirely uselessfor bonding surfaces.Gelling of neoprene cement during storage has been avoided, before thepresent invention, by manufacturing the cement in two parts and storingeach part separately. A non-vulcanizing, solvent base cement portion wasformed of neoprene 'andrnodifyin'g ingredients such as zinc oxide andcarbon black dispersed in a solvent butwithout a vulcanizationaccelera-i to'r. The base cement portion and accelerator portion werestored separately until ultimate usefwhereupon the base cement and theaccelerator portion were mixed, and

the resulting vulcanizable cement was. applied immediately to thesurfaces to be bonded. Such two-part 'cement is cumbersome to store,ship and use. Moreover, such cement is unsatisfactory particularly,because in the event thatall of the vulcanizable adhesive is not usedimmediately after the accelerator is added, the portion not so usedwillgel in a matter of hours, and thus become unusable.

A proposal has beenQmadeto reduce the gelling tendency of neoprenecements by reducing the amount of vulcanization accelerator usedtherein. In order to form a satisfaetorybond between two cemented surefaces, it is necessary to vulcanize the cement. How ever, the use of aless quantity of accelerator requires that the step of vulcanizing thecement be increasedan undesirable length of time. Moreover, areductio-n'of the amount of accelerator in a cementjreduc'es thestrength of the vulcanized bond formedby such a cement.

2,875,184 Patented Feb. 24, 1959 Neoprene as used herein refers topolymers of chloro butadiene as sold by the E. I. du Pont ,de Nemours &Company under that trade name. v

The most successful of the prior art neoprene cements to resist gellingis compounded with a vulcanization accelerator combination ofdibenzylamine and carbon disulfide. Such a cement is disclosed in U. S.Patent 2,514,192. This cement, although having some resistance togelling for short periods of time, has a very slow rate of vulcanizationand for that reason, is unsuitable for most applications.

An object of the present invention is to' provide a neoprene cementwhich will not gel under normal conditions of storage but which has arapid rate of vulcanization.

Another object of the invention is to provide a neoprene cement whichforms a vulcanized bond of greater strength between two surfaces thanhas herctofore been possible.

A further object of the invention is to provide a neoprene cementresistant to gelling during storage, but capable of producing a strongervulcanized bond between two surfaces in reduced vulcanization time.

A further specific object of the invention is to provide a neoprenecement which contains as an accelerator an aliphatic or cycloaliphaticamine, an amino-alcohol and a carbon disulfide.

The amino'alcohol of the invention is preferably selected from the loweralkylamino-alcohols such as the ethanol amines whichineludemonoethanolamine,

diethanolamine "and triethanolamine. Other satisfactory amino-alcohols"are mono-propanolamine; jdiprop anolamine and tripropanolami ne as'well as mixtures of. the propanolamines with each other and otheramino-alcohols. Also useful are butanolamines such as isobutar'rolamineand other amino-alcohols such as -2-amino-2- methyl propanol. Theamino-alcohol or mixture of amino-alcohols selected for the novel cementismixed with carbon disulfide either before or after addition tothecem'entas referred to laterherein. W

.Another portion .of tlretaccelerator.may be selected from the lower,secondary. and tertiary aliphatic, cycloaliphatic or saturatedheterocyelic amines as well as substitutedderivatives thereoflfAmong theamines satisfactory for use in the .invention are diamylamine,triamylatnine, tributylamine, dibutylamine, propylamin'e,

it dipropylamine, tripropylamine, .diethylamine, "triethylw amine,di-(Z-ethyl .hcx yl) amine .and dibenzylamine which behaves chemicallyas an alkyl amine. :Also

satisfac'tory are eyclohexylamine, dieyclohexylamine,

benzyl-diethylamine, and .tri n propylamine. The aminoalcohol and thesecondary or tertiary amine may be mixed beforebeingaddedto the cementor may he added'to the Tcementsinglyasdesired.

In one manner of preparing a cement (of :the :inven- 'tion neoprene isma'sticated on 'a two-roll mixing'rmill,

and ingredients such as; carbon :black, antioxidant, and oils are addedwith continued mastication iuntilta aunito the seam with self-aligninggrips.

form dispersion of ingredients in the neoprene is obtained. The neoprenecompound is removed from the mill and is dissolved by stirring in asuitable solvent such as toluene, until a cement of a concentrationapproximating one pound of neoprene compound for each gallon of cementis produced. The carbon disulfide, the amine and the amino alcohol areadded to the toluene cement. Other methods of mixing are familiar tothose skilled in the art of manufacturing solvent cements and willproduce satisfactory results. Therefore, it is not intended to limit theinvention to the method set forth above.

Among the known solvents useful for neoprene cements are aromaticsolvents such as benzene, toluene, xylene and their homologues; ethylenedichloride, trichloroethylene and other chlorinated hydrocarbonsolvents; ester solvents, suchas amyl acetate, butyl formate, butylacetate, ethyl acetate and ethyl propionate; ketones such as methylethyl ketone, isophorone and the like; mixtures of any of the abovesolvents with each other or with gasoline or the Parts by weightPolychlorobutadiene rubber (neoprene) 1 100.00 Carbon black 3.00Antioxidant 2.00

1 Neoprene CG was used but neoprene AC, neoprene GN, neoprene KN, KNRand other types are acceptable.

The mixed stock was dispersed in toluene to make a base cement with atotal solids concentration of approximately 10% by weight. To this basecement, various amounts of ingredients were added and dispersed, and theresulting cements were tested in the oven test and dead weight test, allsamples being air-cured at room temperature. The added ingredients andtest results are given in Table I.

In Table I and in the following tables, all parts are by weight basedupon 100 parts of neoprene in each cement.

Table I Sample No. Control Cement Monoethanolamine 3. 66 3. 66 3. 66 3.66 3. 66 3. 65 3. 66 Dlbenzylamlne" 6. 16 6. 16 6. 16 4. 88 3. 70 3. 706. 16 3. 70 Dlethylamine... 1. 70 3. 3.40 3. 40 2. 55 1. 70 2. 55 ZincButylxenthate. 6.00 6. 00 4. 78 3. 58 3. 58 6. 40 3. 58 Carbon Dxsulflde14. 00 22. 6 22 6 15.0 11.30 11.30 37. 6 22. 6 Deal; Wt. Test (48 hr.cure): r

Pounds 20 76 80 54 58 72 l 74 94 0 2 2 1 2 2 2 '2 32 40 52 0 35 22 55 6hrs. No No No No No 2 21 Test Test Test Test Test Days Days Run Run RunRun Run to the art.

In order to test the cements of the invention, tests were made accordingto the following specifications:

OVEN TESTS A container holding a sample of the cement to be tested isplaced in an atmosphere of hot air at 158 F. or at room temperature(approximately 75 F.), and the time required for the appearance of asolid gel formation in the cement is recorded.

DEAD WEIGHT TEST The surfaces of two strips of rubberized fabric 12 x 4%inches are cleaned with an aromatic solvent and a margin of at least /1of an inch along one long edge of each strip is cemented withtheneoprene adhesive to be like: and commercial mixed solvents forneoprene known overlapping seam which is rolled out with n rollerstitcher to produce intimate'contact of the cemented surfaces and toexpel air bubbles. The seams thus formed are aircured at a desiredtemperature for. the length, of time of the test; .Sample specimens twoinches in width mean at right angles to the seam. The test specimen isplaced inan atmosphere of hot air at 140 F. and gripped parallel A loadis applied to the grips normal to the seam at a-rate of 30 pounds perminute in an attempt to pull the seam apart. Results are reported inpounds of load and in time in minutes'and secondsrequired for separationof the seam.

Standard specification requires an air drying adhesive to cure'withintendays and to have a minimum strength .of dead weight test of 60. lbs.when tested at 140 F.

The amino-alcohols substituted for monoethanolamine Cementsincorporating the novel accelerators and stabilizers as shown by Table Ihad gelling resistance superior to the prior art control cement and alsowere faster curing.

Improved results over the prior art are also obtained upon substitutingother amino-alcohols for monoethanolamine. The cements shown in Table IIwere prepared in the manner previously described and were tested withthe improved results shown.

Table II Sample No. v

Monoethanolarnlne-.-.' 3.66 Dibenzylamine 3.70 3.70 3.70 3.70 3.70Diethylamine 2. 55 2. 55 2. 55 2. 55 2.55 Zinc Butylxanthate. 3. 58 3.58 3. 58 3. 58 3. 68 Carbon Disu1fide. 37. 6 37 6 37. 6 37. 6 37. 6Diethanolamiue 6 28 Triethanolamine 8.92 Isobutanolaminm- 5.322-amino-2-methylpropanol... 5. 32 7 Dead Wt. Test (Sample cured 10 daysat F.):

in the cements of Table 11 gave adhesives with improved resistance togelling and improved rate of vulcanization characteristics over theprior art adhesives, but the aminoalcohols shown are given as examplesonly and the invert tion is not intended to be limited thereto.

The advantages of the invention are found also when the reactionproducts of the various amines with carbon disulfide are substituted forthe amines themselves.

An indicationof the degree of improvement obtained by use of an excessof carbon disulfide in the cement with the reaction products-of theamines ofthe invention with carbon disulfide is seen by reference toTable III.

Cements 19" to inclusiveusing accelerators of the above concentrationwere mixed" as' previously described and tested with results; asindicz'tte'd. These cements provedto be superior to prior art cements;

Tertiary amines aloneor mixed with themselves: or other amines may becombined with carbon disulfi'de and an amino alcohol to obtain theadvantages of the invention.

Table III Sample No.

Zinc Butylxanthate ...s.5s -3. 58 3. 58 3.58 3.58 3.58 Dibenzylamlne...1.85. 1.85 Diethylamine L. 1.27 1.27 Monoethanolamine. Carbon Disulfide,22.6 22.6 22.6 Diethylammonium Diethyldithiocarbamatm. 6.64 6:64 6.64 6.64 6.64 6.64 MonoethanolammoniumEthanoldithioearbamap 1 5.92 5.92 5.92 592 5.92 5.92 Dead Wt. Test (Cured 20 hrs. at 75 F.):

Pounds 42 46. 40 l 56 46 59 in 1a---- 1 1 1 1 1 1 Sec 12 18 e 42 1s 64Days to gel in 158 F., Oven. 9 4 7 11 218, 9

The cements listed in Table III were mixed in the pre- Table V scribedmanner and tested. The results indicate that the novelaccelerator-stabilizer combination permits the use Sample of thereaction products of the amines and carbon disulfides as well as withincreased amounts of carbon disul- 26 7 28 29 fide to give a strongervulcanized bond with httle loss 11 Dibenzylamine 6'12 gelltngresistance. All of the cements of Table III show 11\ )I1ethy%min1e3:671v either improved cure or improved gelling resistance over ggggiggg gge f 1 22. 4

enzy 1e y amme 4. 25 the prior art neonrene cements. Trmmmpmmme; u 5.81n The inventlon 1s workable with concentrations of caret yla me -t, 4.36Dead Wt. Test (Sample cured 48 hrs. at bon dlsulfide over a wlde rangebased on the neoprene F.): content of the cement. Table IV lists cementstested 82 showing the effects of varying the concentration ofcar- 2 g: gbon disulfide while maintaining the concentration of the 6 6" otheraccelerators constant.

Table IV Sample No.

Zinc Butylxanthate 2. 52 2. 52 2. 52 2. 52 2. 52 2. 52 2. 52Dtbenzylarntnauu 2. 60 2. 60 2. 60 2. 60 2. 60 2. 6O 2. 60 D1ethylamme1.19 1.19 1. 19 1. 19 1.19 1.19 1.19 'cltglatzrgoetlgilolltzirgine $-562.56 2. 56 2. 56 2. 56 on sn e. .92 15. 90 23:80 2 Dggglrjvlgt. Test((lured 20 hrs. at n 8 40 31 Polirids 51 5o 47 4s 64 41 T1136? 4% 4( 3 12 1 4 .26 8 Days to gel in 158 F., Oven 10 44 5 10: 23

All of the above cements when tested were better than the-prior artcements in rate of cure or gel resistance.

In addition to the use of aliphatic amines in the cement of theinvention the use. of cycloaliphatic amines singly or in mixture withother amines'is possible as is shown by Table VI.

Table VI Sample No.

Dibenzylamine 6.12 Dlethylemine 3. 67 Mnnnpthannlaminn 3. 67 3. 67 3. 67Carbon Disulfide 22.4 22. 4 22.4 Oyclohexylarnine- 4. 67Dicyclohexylamine DeFad Wt. Test (Sample cured 48 hrs. at 75 in thefollowing table:

Table VIII Sample No.

Zinc Butylxanthete 3. 58 3. 58 3. 68 Dibenzy ine 3. 7 Mnnnnthnnnlnminn3. 66 Di-isopropylnmina 4. 4 Carbon Dlsnlflde 22. 6Diisopropylammonium-Diisopropyldithiocarbamate 8. 32Dimethylammonium-Dimethyldithiocarbamate 4. 97 Monoethanolemmoniumethanoldithiocarbamate- 5. 93 5. 93 Dent Wt. Test (Sample cured 20hrs.at 75 F.)

Pounds 98 65 66 Time- 3 2 2 Sec... 16 10 11 Days to gel in 8 13 13 Thesecements were prepared from the base cement as previously described andexhibited properties superior to the prior art neoprene cements.

Only relatively small proportions of the amino alcohol and of thealkylamine, based. upon the neoprene content of the cements of theinvention, are required. To gain the advantages of the invention, thealiphatic and cyclealiphatic amines are present preferably in amountsfrom 15% by weight on the neoprenewhile up to and more will give theadvantages of the invention. The amino-alcohol is employed in quantitiesof 20% or more on the same basis with a range of 1-5% preferred. Theactual amounts of these amines utilized, are in line with the amounts ofvulcanization accelerators normally eniployed in neoprene cements. As isindicated above, carbon disulfide could be included in the cement withthe amino alcohol and amine, in a sufficient amount to form appreciablequantities of the dithiocarbamate reaction products Alternatively, as isbrought out above, free Table VII Sample No..

Zinc butylxanthate 6. 4 6. 4 6. 4 6. 4 6. 4 6. 4 6. 4 6. 4 Dlbenzylame..- 6.2 6.2 6.2 6.2 6.2 6.2 6.2 6.2 D1ethylemlne. Monoethanolamin .73.7 3.7 3.7 3.7 3.7 Carbon Disulfide- 6 37. 6 6 22. 6 22. 6 22. 6Dilsopropylamlne 4. 4 7. 3 Dl-n-butylamlne- T-butylamine 2.20 Dl-n-amymln 4. Dt-(2-ethylhexyl)amine 7. 22 Dimethylamine. 1.34 Dead Wt. Test(Sample cured 48 hrs. at

The above listed samples were prepared usingthe base cement and testedas indicated. All of the above cement showed properties superior to theprior art.

The reaction products of amines other than diethylamine anddibenzylamine will function satisfactorily in a cement of the inventionas shown by the following table:

- I0 carbon disulfide is unnecessary in cement when thecarbon disulfidereaction products of the arnino-alcohol and the alkylamine are utilized.p i V The wide range of use of the accelerator in the preferred form ofthe invention isIsho'wn byfthefollowing Table IX Sample No.

Zlncbutylxanthate 4. 3 4. 3 4. 3 4. 3 4. 3 4. 3 4. 3 lbenzylamme 2. 464. 92 7. 38 9. 84 12. 3 14. 76 17. 22 Monoethanolamine 2. 44 4. 88 7. 329. 76 12. 2 14. 64 17. 08 iethylamlue 1. 70 3. 40 5. 6. 80 8. 5 10. 211. 9 Carbon dlsulfide 15. 9 15. 9 15. 9 15. 9 15. 9 15. 9 15. 9 DeadWeight 140 F.; Aged hrs. 75 F.:

Pounds 18 44 67 34 32 20 13 Time- Min 0 1 2 1 l 0 0 Sec 37 27 14 9 4 39Gel Test No gel N o gel N o gel N o gel No gel No gel N o gel Days in158 F., Ove 10 10 10 l0 10 10 10 It will be seen that all reasonablequantities of the novel accelerator of the preferred form of theinvention reacting to give gel time and dead weight tests superior tothe prior art cement shown in sample 6. It is apparent that the amountsof the accelerators used are relatively small as compared to the amountof neoprene present and in the terms of the rubber compounder theaccelerator is used in relatively small proportions in the new prenecement.

What is claimed is:

1. A vulcanizing cement containing a rubbery polychloroprene, a solventfor said polymer and as an accelerator, relatively small amounts ofcarbon disulfide, a lower alkylamino-alcohol, and at least one lowerpolyalkylamine selected from the group consisting of lower aliphaticamines and lower cycloaliphatic amines.

2. A vulcanizing cement containing a rubbery polychloroprene, a solventfor said polymer and as an accelerator, relatively small quantities ofcarbon disulfide, an ethanolamine and at least one lower polyalkylamineselected from the group consisting of lower aliphatic amines and lowercycloaliphatic amines.

3. A vulcanizing cement according to claim 2 wherein the ethanolamine isa monoethanolamine.

4. A vulcanizing cement according to claim 2 wherein the ethanolamine isa diethanolamine.

5. A vulcanizing cement according to claim 2 wherein the ethanolamine isa triethanolamine.

6. A vulcanizing cement according to claim 1 wherein the loweralkylamino alcohol is isobutanolamine.

7. A vulcanizing cement according to claim 1 wherein the loweralkylamino alcohol is 2-amino-2-methylpropanol.

8. A vulcanizing cement containing a rubbery polychloroprene, a solventfor said polymer and as an accelerator relatively small 9. A vulcanizingcement according to claim 8 wherein the lower polyalkylamine is apolyethylamine.

10. A vulcanizing the lower polyalkylamine is dibenzylamine.

11. A vulcanizing cement according to claim 8 wherein the lowerpolyalkylamine is a polypropylamine.

12. A vulcanizing cement according to claim 8 wherein the lowerpolyalkylamine is a polybutylamine.

13. A vulcanizing cement according to claim 8 wherein the lowerpolyalkylamine is a polyamylamine.

14. A vulcanizing cement containing a rubbery polychloroprene polymer, asolvent for said polymer and as an accelerator, relatively small amountsof carbon disulfide, an ethanolamine and a cycloaliphatic amine.

15. A vulcanizing cement according to claim l2 wherein thecycloaliphatic amine is dicyclohexylamine.

1 6. A vulcanizing cement containing a rubbery polychloroprene, asolvent for said polymer and as an acquantities of carbon disulfide, anethanolamine and at least one lower polyalkylamine.

cement according to claim 8 wherein celerator relatively small amountsof an ethanolamine and at least two polyalkylamines.

17. A vulcanizing cement according to claim 14 wherein thepolyalkylamines are diethylamine and dibenzylamine.

18. A vulcanizing cement according to claim 14 wherein thepolyalkylamines are dibenzylamine and diisopropylamine.

19. A vulcanizing cement according to claim 14 wherein thepolyalkylamines are dibenzylamine and di-nbutylamine.

20. A vulcanizing cement according to claim 14 wherein thepolyalkylamines are dibenzylamine and T- butylaminc.

21. A vulcanizing cement according to claim 14 wherein thepolyalkylamines are dibenzylamine and di- (Z-ethylhexyl) amine.

22. A method of preparing a quick-curing rubbery polychloroprene cementcomprising the steps of disso1v-- ing rubbery polychloroprene in asolvent and adding as an accelerator relatively small proportions ofcarbon disulfide, a lower alkylamino-alcohol and at least one lowerpolyalkylamine selected from the group consisting of aliphatic andcycloaliphatic amines.

23. A method of preparing a quick-curing rubbery polychloroprene cementcomprising the steps of dissolving the rubbery polychloroprene in asolvent and adding as an accelerator relatively small amounts of carbondisulfide, an ethanolamine and at least one lower polyalkylamine.

24. A method of preparing a quick-curing rubbery polychloroprene cementcomprising the steps of dissolving the rubbery polychloroprene in asolvent and adding as an accelerator relatively small amounts ofcarbon-disulfide, an ethanolamine, diethylamine and dibenzylamine.

25. A method of preparing a quick-curing rubbery polychloroprene cementcomprising the steps of dissolving the rubbery polychloroprene in asolvent and adding as an accelerator not over 32 parts of carbondisulfide, not over 20 parts of an ethanolamine, not over 15 parts ofdibenzylamine, and not over 7.5 parts of diethylamine.

26. A method of preparing a rubbery polychloroprene cement according toclaim 24 wherein the ingredients of the accelerator are mixed togetherbefore being added to the cement.

27. A method of preparing a rubbery polychloroprene 65 cement accordingto claim 25 wherein the ingredients of the accelerator are mixedtogether before being added to the cement.

References Cited in the file of this patent UNITED STATES PATENTS2,163,611 MacDonald June 27, 1939 2,340,650 Dean Feb. 1, 1944 2,514,192Tann July 4, 1950 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTIONPatent No, 2,87%184 February 24, 1959 William E, Tann It is herebficertified that error appears in the -printed specification of the abovenumbered patent requiring correction and that the said Letters Patentshould read as corrected below.

Columns 3 and 4, Table I, eighth column thereof, under Sample N05 6;,

next to last line, for the figure; "2" read 21 we Signed and sealed this21st day of July 1959a (SEAL) Attest:

KARL H, AXLINE ROBERT C.. WATSON Attesting Oflicer Commissioner ofPatents

1. A VULCANIZING CEMENT CONTAINING A RUBBERY POLYCHLOROPRENE, A SOLVENTFOR SAID POLYMER AND AS AN ACCELERATOR, RELATIVELY SMALL AMOUNTS OFCARBON DISULFIDE, A LOWER ALKYLAMINO-ALCOHOL, AND AT LEAST ONE LOWERPOLYALKYLAMINE SELECTED FROM THE GROUP CONSISTING OF LOWER ALIPHATICAMINES AND LOWER CYCLOALIPHATIC AMINES.